Error -200524 Channels in Data Doesn't Match Channels in Task

Updated Nov 16, 2018

Reported In

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

  • I am trying to write to multiple channels and getting the following error. Can I not write to multiple channels at the same time?
  • Why do I receive the following error when I try to use the DAQ Assistant Express VI or DAQmx Write for digital or analog output tasks? 

Error -200524 occurred at an unidentified location
Possible reason(s):
1.  Write cannot be performed, because the number of channels in the data does not match the number of channels in the task.

2.  When writing, supply data for all channels in the task. Alternatively, modify the task to contain the same number of channels as the data written.

Solution

If you are using the DAQmx API functions to configure a Digital Output, make sure you have selected the correct value for "line grouping" in DAQmx Create Virtual Channel. This can be set to "one channel for all lines" or "one channel for each line," so make sure you have selected the option that matches your input to DAQmx Write. A virtual channel is created for the physical channels you want to interact with. A virtual channel is a collection of property settings. See the Channels and Tasks in NI-DAQmx article to learn more about channels in LabVIEW.

If using DAQ Assistant, the problems can be resolved by ensuring that your data has the appropriate number of channels to match the channels configured in the DAQ Assistant.  This is described in greater detail within the "Additional Information" section below.

Additional Information

When writing using the DAQ Assistant Express VI or DAQmx Write, you must supply data for each channel that is configured in the task. 

For example, if your task has 5 channels, you must provide 5 channels of data.  If your task has 3 channels, you must provide 3 channels of data.   

Suppose you configure the VI to generate data on lines 0, 1, and 2 shown in the figure below. This will create three channels in the task, and so we should create data that also has three channels.


If instead, we write more or fewer channels, the error will show the difference in the expected and received number of channels.

Figure 1: LabVIEW example of digital data mismatch

Figure 2: LabVIEW example of analog data mismatch

Figure 3: Resulting error from both cases displays the channel difference
 

You may also receive an error when you use a port configuration and are attempting to write with multiple channels. You should have as many channels as ports and the data type of the channel will be an unsigned int whose value in binary controls the each line. 


Figure 4: LabVIEW example of digital data mismatch\

Figure 5: Error from digital data mismatch


Figure 6: LabVIEW example of the correct way to write to a port

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